Odorant for refrigeration



-for such purpose.

Patented Nov. 1, 1932 .A'LmANDER DOUGLAS MACALLUM, OF NIAGARA THE BOESSLER & HASSLACHER. CHEMICAL COMPANY,

PORATION OF DELAWARE NEW YORK, ASSIGNOB. T0

ODORANT FOB; nnrnrcm'rron No Drawing.

This invention relates to the use of a. warning agent for refrigerants escaping from refrigerating systems and more particularly from systems in which relatively inodorous refrigerants are used. In case of leaks in large refrigerating systems, such as multiple-unit, direct expansion systems in apartment "houses, relatively high and dangerous concentrations of refrigerant in the air may result. If the'refrigerant is not readily detected by its odor, persons breathing air containin it may not become aware of such leaks he lated.

The object of my invention is to afford means of warning of leakage in refrigerating systems by incorporating in the refrigerant a small pro ortion of an alkyl ester of bromacetic aci the vapor of which will escape with the refrigerant and irritate the eyes.

Substances haying odorous or irritating properties have heretofore been incorporated in gases to enable leak detection. Practically any stable odorantor irritant with a sufliciently high vapor pressure may be used However, for usein a refrigerant, such a warning agent must possess special properties. It not only -must have an appreciable vapor pressure at room temperature, but also must be readily soluble in the refrigerant at the lowest temperature occurring in the refrigerating system, have a freezing polnt below this temperature, be stable under conditions occurring 1n the sys- -tem, have little or no corrosive effect on metals, and must not react with the refrigerant.

I have found that the alkyl esters of bromacetic acid which are lachrymators possess properties which make them especially suited as warning agents in refrigerating systems.

- I have used from 0.5 part to 4 parts by weight of alkyl bromacetate to 100 parts of liquid refrigerant with good results. This invention is however not limited to these proportions as other proportions may be satisfactory, especially under conditions other than those occurring in my experiments. In gen eral, the best proportions for warning pur-,

poses depends upon the nature of the refrigfore toxic quantities have accumu-.

Application filed September 4, 1831. Serial No. 561,309.

erant and the type of refrigerating machine. The intensity of the warning effect may be varied by varying the bromacetate content of the refrigerant. Various types of refrigeration systems may require different proportions of the warning agent; for'instance the float-chamber type of compression refrigerator may require more bromacetate than the direct expansion ype using a diaphragm expansion valve. prefer in general to use 1 part by weight of liquid alkyl bromacetate to 100 parts by weight of the liquid refrigerant. The bromacetate may be introduced either before or after charging the sys tem with refrigerant. v

Refrigerants with which an alkyl bromacetate may be used as a warning agent comprise those which readily dissolve the sub stance at the lowest temperature occurring in the refrigerating system, and which do not react with it. An alkyl bromacetate may be used satisfactorily as a warning agent, for v example, in a refrigerating system employing methyl chloride as a refrigerant. By means. of my invention, persons exposed to concentrations of 0.1% by volume, or even less, of methyl chloride in air are quickly warned of its presence. The invention therefore provides a means for warning persons of concentrations of this refrigerant which are far less than any which would endanger the health, if exposure is limited to any reasonabletime. When refrigerant gas containing about 0.5% by weight of an alkyl bromacetate has accumulated in a room, an occupant first feels a stinging sensation in the eyes; when a concentration of 0.1% by volume of refrigerant in the room is reached, the eyes water copiously and within a few 'minutes it becomes necessary for the person to leave the room. When the eyes are washed outwith sodium bicarbonate solution, the unpleasant sensation is relieved.

A particularly goodfeature of these warning agents is that the irritation not only occurs immediately, but that it becomes greater the longer the exposure, and a tolerance is not established. A further advantage is that warning effects result from leaks from both the high and low pressure sides of a compression type refrigerating system, showing that the bromacetates do not ac-' v the metals was very slight. During a period of 30 days, continuous use of this warning agent in a household refrigerator, there were neither signs of corrosion nor of polymerization. It was also found that the warning effect of the refrigerant containing ethyl bromacetate was substantially unchanged after the 30 day period.

Eammple 1 Methyl chloride containing 1% by weight of tertiary butyl bromacetate was vaporized into a closed room to form" a concentration of about 0.1% methyl chloride'in the air. After the atmosphere of the room had been stirredby an electric fan for 15 minutes, two .ob servers entered but were forced out of the room in slightly less than one minute by irritation of the eyes.

Example 2 The experiment described in Example 1 was repeated, using isopropyl bromacetate in place of the butyl bromacetate. In this case the two observers were forced to leave the room within 5 seconds because of an unusually severe irritation of theeyes.

Example 3 A household refrigerator was charged.

with methyl chloride containing 1% ethyl bromacet'ate by weight. After continuously operating the refrigerator for two days, a measured sample of the refrigerant wasremoved from the high pressure side of the pump. This sample was vaporized in a closed test room. to give a concentration of about 0.1% methyl chloride in the air. After the atmosphere of the room was stirred by an electric fan for 15 minutes, two observers entered but wereforced out of the room in about 90 seconds by irritation of theeyes.

Example 1;

The experiment described in Example 3 was repeated, except that the refrigerant was removed from the low pressure side of the machine. In this case, the observers were forced to leave the testing room in less than 60 seconds.

E'bample 5 The experiment described in Example 3 was repeated, except that 1% of methyl bromacetate was used as warning agent in place of ethyl brolnacetate and the machine was operated 5 days before making the test. The eye irritation forced two observers from the testingroom in 7 and 9 minutes, respectively.

I claim:

1. A composition of matter comprising a relatively inodorous refrigerant containing a la'chrymatory alkyl bromacetate in amounts suitable for warning purposes.

2. A composition of matter comprising a relatively inodorous refrigerant containing, in amount suitable for warning pur ses, one of the substances selected from t e group comprising ethyl bromacetate, methyl bromacetate, tertiary butyl bromacetate and isopropyl bromacetate.

v 3. A composition of matter comprising a halogenated hydrocarbon refrigerant con- .taining, in amount suitable for warning purposes, one of the substances selected from the group comprising ethyl bromacetate, methyl bromacetate, tertiary butyl bromacetate and isopropyl bromacetate.

4. A composition of matter comprising a halogenated hydrocarbon refrigerant containing 0.54.0% of ethyl bromacetate.

5. A com osition of matter comprising methyl chloride containing about 1% of ethyl bromacetate. I

6. A composition of matter comprising a halogenated hydrocarbon refrigerant containing 0.5-4.0% of isopropyl bromacetate.

7 A composition of matter comprisin methyl chloride containing about 1% o isopropyl bromacetate.

Signed at Niagara Falls in the county of Nia ara and State of New York this 1st day of S eptember, A. D. 1931.

A. DOUGLAS MACALLUM. 

